Saturnís odd moon Hyperion

Fig. 10.27 . This stunning view of Saturnís asymmetric, tumbling, impact-cratered moon Hyperion reveals numerous sharp-edged craters, which make the moon look like a giant sponge. Hyperionís unusual appearance can be attributed to the fact that it has an exceptionally low mean mass density, of just 567 kilograms per cubic meter, with a large porosity of 0.46 and a weak surface gravity. In other words, the moon seems to contain a lot of empty holes, somewhat like a sponge. This processed, false-color view combines images taken at infrared, green and ultraviolet wavelengths from the Cassini spacecraft during a close flyby on 26 September 2005. (Courtesy of NASA/JPL/SS.)